1. Field of the Invention
The present invention relates, in general, to variable capacity rotary compressors and, more particularly, to a variable capacity rotary compressor which has a pressure controller to allow an internal pressure of a compression chamber where an idle operation is executed, to be equal to an internal pressure of a hermetic casing.
2. Description of the Related Art
Recently, a variable capacity compressor has been increasingly used in a variety of refrigeration systems, such as air conditioners or refrigerators, so as to vary a cooling capacity as desired, thus accomplishing an optimum cooling operation and a saving of energy.
An earlier patent disclosure dealing with a variable capacity compressor is found in U.S. Pat. No. 4,397,618. According to the patent, a rotary compressor is designed to vary a compression capacity thereof by holding or releasing a vane. The rotary compressor includes a casing in which a cylindrical compression chamber is provided. A rolling piston is installed in the compression chamber of the casing to be eccentrically rotated. Further, a vane, designated as a “slide” in U.S. Pat. No. 4,397,618, is installed in the casing, and reciprocates in a radial direction while being in contact with an outer surface of the rolling piston. A vane holding unit, which includes a ratchet bolt, an armature, and a solenoid, is provided at a side of the vane to hold or release the vane, thus varying the compression capacity of the rotary compressor. That is, the vane is held or released in response to a reciprocating movement of the ratchet bolt controlled by the solenoid, thus varying the compression capacity of the rotary compressor.
However, the conventional variable capacity rotary compressor has a problem in that it is designed such that the compression operation thereof is controlled by holding or releasing the vane for a predetermined period of time, so it is difficult to precisely vary the compression capacity to obtain a desired exhaust pressure.
Further, the conventional variable capacity rotary compressor has another problem in that the ratchet bolt holding the vane is designed to enter a side of the vane and be locked to a locking hole formed at the vane, so it is not easy to hold the vane which reciprocates at a high speed when the compressor is operated, thus having poor reliability.